HELIUM. 
From the experience thus obtained it was possible to draw up specifica- 
tions for a commercial: plant to deal with about 56,500 cubic feet of 
gas per hour at normal temperature and pressure.+ Six of these machines _ 
_ would deal with 9,500,000 cubic feet of gas daily—the average supply 
of natural gas at Calgary. The cost of a commercial plant. for treating 
the whole supply from the Alberta field would probably be less than 
£150,000, assuming an efficiency of 80 per cent. (i.e., a recovery of 80 
per cent. of the helium content of the natural gas), and allowing for 
salaries, running costs, amortization, &c., helium could be produced in 
Alberta at less than £10 per 1,000 cubic feet, excluding the cost of 
cylinders and transport. From data so far ascertained, it is probable 
that the potential yearly supply of helium from all sources within the 
Empire would not suffice to keep more than a very few of the larger 
airships in commission, even if diluted with 15 per cent. of hydrogen. 
it might be used to fill fireproof compartments adjacent to the engines 
if it were decided to install these within the envelopes of larger airships. 
In the course of this work, a number of collateral problems were 
investigated. It was found, e.g., that for aeronautical purposes — 
hydrogen could be’ mixed with 15-20 per cent. of helium without the 
mixture becoming inflammable or explosive in air. The permeability 
of rubbered balloon fabrics for helium was shown to be about 0.71 of 
its value for hydrogen. or skin-lined fabrics, the permeability to 
hydrogen and thelium was about the same. Thin soap films were found 
to be about one hundred times more permeable to hydrogen and helium 
than rubbered balloon fabrics, but untreated cotton fabrics, when 
wetted with distilled water, were but feebly permeable to these gases. 
Tt was found that rapid estimations of the amount of helium in a gas 
mixture could be made with a pivoted silica balance, a Shakspear 
katharometer, or a Jamin interferometer. The latent heats of methane 
and ethane were determined, and also the composition of the vapour 
and liquid phases of the system methane-nitrogen. It was ascertained 
that helium containing as much as 20 per cent. of air, oxygen, or 
nitrogen can be highly purified in large quantities by simply passing it 
at slightly above atmospheric pressure through a few tubes of coconut 
charcoal kept at the temperature of liquid air. In the spectroscopy of | 
the ultraviolet, helium was found to be exceptionally useful. | 
Among the suggested possible applications of helium are its use in 
industry as a filling for thermionic amplifying valves of the ionization — 
type; for filling tungsten incandescent filament lamps, especially for sig- 
nalling purposes where rapid dimming is essential; and for producing 
gas arc lamps in which tungsten terminals are used, as in the “ Pointo- 
lite” type. However, both of these varieties of lamps possess the 
defect of soon becoming dull owing to the ease with which incandescent 
tungsten volatilizes in helium and deposits on the surface of the enclos- 
ing glass bulbs. As regards illumination, helium are lamps possess an 
advantage over mercury are lamps in that the radiation emitted has 
strong intensities in the red and yellow portion of the spectrum. 
Nutting has shown that Geissler tubes filled with helium are eminently 
suitable, under certain conditions, for light standards in spectrophoto- - 
metry, but the amount of the gas which could be used in this way is - 
+A full account of the apparatus employed, with diagrams, is given in the Journal of the Society 
of Chemical Industry, July, 1920. “ 
677 
